Dental mandrel



Patented July l5, i924.

rtree` JGHN E. CANNING. OF DENVER, @GLOB-ADO; S. C. WARNER ADMINISTRATOR F SAID JOHN' E. CANNING, DECEASED, ASSIGNOR TO THE DENTAL SPECIALTY COMPANY,

A CORPORATION 0F COLORADO.

DENTAL MANDREL.

Application filed February 18, 1922. Serial N'o. 537,400.

Denver and State of Colorado, have invented certain new and useful Improvements in Dental Mandrels; and I do declare the following to be a full, clear, and eXact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the characters of reference marked thereon, which form a part of this specification.

This invention relates to dental mandrels and has special reference to a means whereby the grinding disc or wheel can be securely held in place and prevented from coming loose regardless of the direction of rotation.

Grinding discs or wheels are usually secured to the end of the rotating mandrel by means of a screw which passes through the disc and extends into the end of the mandrel, the clamping Aaction of the screw being relied upon to prevent the disc from turning.

It has been found, however, that when a disc is clamped to the end of a mandrel by means of a screw in the manner described, it will stay in place as long as the disc is rotated, in such aV direction that the tendency is to tighten the screw, but that when the disc is rotated in the opposite direction the screw will loosen and permit the disc to rotate and occasionally to fall off or break.

I have found that by adding to the comhina-tion another element that I am able to rotate my disc in either direction without loosening the same, which is a result that has long been desired and often sought but never, to my lmowledge, before attained.

In order to more clearly describe my invention, I shall have reference to the accompanying drawing in which- Fig. l shows a section of a mandrel and grinding disc, partly assembled, in accordance with my invention.

Fig. 2 shows the mandrel and disc in fully assembled relation; and

Fig. 3 shows a modified form of screw.

The same reference character will be used to designate the same parts throughout the several views. l

Numeral l representsa mandrel which is provided. at its outer end vwith an enlarged portion 2 against the outer surface of which the carborundum grinding disc 3 Yis clamped by means of a screw 4 which projects through the central opening in the disc and extends a considerable distance into the mandrel 1.

In the prior 'art the disc 3 has been clamped between the end of the mandrel l and the head of the screw 4, by which means the disc is satisfactorily retained in place as long as the direction of rotation is such that it tends to'- tighten the screw 4, but if the rotation is in the opposite direction, experiments have proven that the disc will Vsoon become loose and inoperative.

To have a grinding disc become loose while it is employed within a patients mouth may result in a seriousaccident, as the disc may break and the flying particles cause great injury.

I have found that by the simple eX- pedient of adding a spring washer 5 between the outer surface of the disc and the head of the screw 4 in the manner shown in Fig. l, and'then tightening the screw until the washer assumes a substantially flat surface, as indicated in Fig. 2,. that the disc may be safely rotated in either direction without becoming loose. a

I have proven the above assertion by innumerable experiments, and have. conclusively demonstrated that by the simple eX- pedient above described, the much desired reversible grinding disc can beV attained.

I want to call particular attention tothe `fact that my washer 5 is not a lock washer l am aware that the expedient employed by me is very simple, but it accomplishes ay useful resnlt, and l therefore ,desire proection for my discovery under the patent BJWS.

I `have shown my springrwasher 5 as being made .of an ordinaryrwasher Atransversely curved as indicated in Fig. 1, but the Washer may be made in many diii'erent Ways and the one shown is illustra-tive only "as almost any kind of spring yyashercap heemployed.

111 Fis 3 I ,here @hewn .e ,Screw .-,V in which spring manner .is ,eut im@ ,nelly from ihr/.Sereni ,heed Aitself ,and .Curved awn- Wardly as shown." This member forrris 2,111.1 element that Perfex-as iibstntielli the Same -uefztpn as the s ries washer ...and has .the advantage that .itlrefiuire 139 Smblns cannet felloif @ed .sei 19st Having non7 described my invention, what I claim as new is- The combination of a -spindle having an axial interiorly threaded bore surrounded by a Hat concentric shoulder, and a perorated disk engaging said shoulder and having flat surf-ace coacting `With the corin QP .fishes relation 'i0 Mi' shell' debf `the spin de.

1.11 Yteslilmeny whereof I @fik my Signetnre.

JOHN @ANNI-NG. 

